As developments of projector related technology advanced, the size of the projection module has been significantly reduced. Therefore, the image projection module can be gradually integrated into other electronic products such as smart phones, lighting devices, or the like in recent years.
Conventional desktop devices having a projection function can be divided into two major categories, wherein one category of the desktop devices comprises an image projection module, an illumination module, and a projection mode switching module, and the projection mode switching module is electrically connected to the image projection module and the illumination module. When a lighting mode is activated, the projection mode switching module turns on the illumination module to provide light beam, and the desktop lighting device can be used as a lamp. In addition, when the projection mode is activated, the projection mode switching module turns on the image projection module to provide the image light beams, thereby forming an image on a surface of the desk, a wall or a screen. Examples of the above desktop device please refer to “Interactive desktop display system for automatically adjusting pan and zoom functions in response to user adjustment of a feedback image” disclosed in U.S. Pat. No. 6,067,112A, “Lamps with projection function” disclosed in R.O.C. Pat. No. TW M452294, “Projection table lamp” disclosed in R.O.C. Pat. No. TW 1472701, and “Projection device with an illumination lamp” disclosed in U.S. Pat. Publication No. US 2012/0262682 A1.
In addition, the other category of the desktop devices merely comprises an image projection module and a projection-mode switching module, wherein the projection mode switching module is electrically connected to the image projection module, and the image projection function and the desktop device shares a common light source. When the projection mode is activated, the projection mode switching module turns on the image projection module to provide image light beams, thereby forming an image on a surface of a desk, a wall or a screen. In addition, when the lighting mode is activated, the projection mode switching module turns off the image projection module, and no more image information would be provided and only a light source is provided, so that the desktop lighting device can be used as a table lamp. Examples of the above desktop device please refer to “Multipurpose micro projection lamp” disclosed in R. O. C. Pat. No. TW M445115, “Projection and control method therefor” disclosed in U.S. Pat. No. 9,158,146 B2, “Lighting device” disclosed in U.S. Pat. Publication No. US 2014/0043544, “Lamp-type projector” disclosed in China Pat. Publication No. CN 203868778, “LED lamp having projector device” disclosed in R. O. C. Pat. No. TW 1387700, “Light emitting devices” disclosed in China Pat. Publication No. CN 100468190, “Combined lamp and movie projector” disclosed in U.S. Pat. No. 5,541,820 A, and “Illumination apparatus” disclosed in U.S. Pat. No. 9,039,234 B2.